A 30-year-old RV is nothing more than a collection of several thousand parts that at the moment, just happen to be occupying adjacent places in space and time. Due to entropy and the fact that RVs are (with a few exceptions) built to less exacting standards than your kid's Lego spaceship, these various parts will separate from one another, as part of the natural order of things. Furthermore, since the design life of the average RV system/system component is 2 minutes 30 seconds, anything 30 years old is still functioning only by the grace of the RV gods.
Some folks enjoy this as a challenge. However, I suspect that you might weary of waiting for tow trucks/spending nights at RV dealerships/taking things apart and putting them back together again more often than you brush your teeth/inventing new swear words. You don't want to introduce yourself to RVing with a 30 year old rig any more than you'd want your teenager to learn to drive in a 1962 Chevy.
Also--the particular rig you're looking at seems reasonably priced. In today's utterly insane RV market, that's a red flag that there's something seriously wrong with it, like a three foot wide hole in the floor (you can see the ground) where the toilet used to be or a roof that looks like it's made of wet Kleenex.